So, I just recently installed a new distributor, including distributor assembly, ICM, pickup coil, cap and rotor. The installation of the distributor completed the ignition rebuild(everything in the ignition system has less than 500 miles). The SES light was on constantly before the distributor install and was always hesitating and bogging down when the throttle was applied from idle it would bog and threaten to die and it's not solved the problem but it has gotten better. Most of the time now it runs like a champ, more power, nearly impeccable throttle response and loads of fun, but it goes back to it's issue of hesitation when the throttle is applied too quickly off of idle or at the bottom of the gear when upshifting. There's doesn't seem to be any rhyme or reason for the shift in performance.

Any suggestions on what to check next to solve my engine issues?

What engine?

When you were getting the SES did you ever check it?

Have you checked it lately?

Are you sure your timing is right? Was the ses light flashing when you set it?

Sounds like you might have a slight vacuum leak. You might check the sensor on the intake too... Check the timing and make sure the disty is locked down tight after you do. Also might clean out the throttle body with some spray cleaner. I went thru some teething issues with my First Fiero and most of it a good tuneup and rebuilt the distributor and lightly sanding the rusty metal parts seemed to wake it up pretty good. The car ran and drove pretty much like a new car after that. Good luck and peace

Pete

quote Originally posted by phonedawgz: What engine? When you were getting the SES did you ever check it? Have you checked it lately? Are you sure your timing is right? Was the ses light flashing when you set it?

Guess I could've been a bit more specific.

https://www.fiero.nl/forum/Forum1/HTML/086050.html <--- Discussion on the engine in question.

I knew the distributor was bad a while ago as it came off the old engine. Here is the thread about the distributor that was replaced.

I coded the engine before I replaced the distributor and it always coded 42. I haven't tried coding it since installing the distributor, and the SES light seems to be independent of the idle/acceleration problem. The idle/accel problem only occurs when the SES light is on, but the SES light has come on without the idle/accel issue occurring, if that makes any sense. I can be cruising at a steady 2000 RPMs in 5th gear and the SES light may come on for 10-20 seconds and go back out and not be seen for the rest of my drive home or to work, which consists of mixed city and highway driving in either direction.

As far as proper timing is concerned, no, I haven't taken a timing light to it because the balancer is clocked wrong on the crank, so it's not perfect, but when it decides to run right it almost runs away.

Here's another thing to check. One of the major problems I had at first was a miss problem that turned out to be a bad brand new distributor rotor button. It actually had a little crack in it and the spark found a way to ground and the car would occasionally run like crap. Once I had redone the disty including removing the shaft and cleaning it with some light sandpaper in my lathe and putting the new coil in it and everything else I could do to it I did a complete tuneup and it still had that miss. It was not until someone suggested it might be a short of some kind that I inspected the cap and rotor for cracks and sure enough there was a little burn mark inside the rotor button. I ran down and got ANOTHER new one and the problem went away. Crazy I know but something to look at. Another thing you might do is run the car with the decklid open in the dark and look for any arc sparks around the plug wires and disty. You can actually see them in the dark pretty good. Good luck and peace

Pete

quote Originally posted by Pete Matos: Here's another thing to check. One of the major problems I had at first was a miss problem that turned out to be a bad brand new distributor rotor button. It actually had a little crack in it and the spark found a way to ground and the car would occasionally run like crap. Once I had redone the disty including removing the shaft and cleaning it with some light sandpaper in my lathe and putting the new coil in it and everything else I could do to it I did a complete tuneup and it still had that miss. It was not until someone suggested it might be a short of some kind that I inspected the cap and rotor for cracks and sure enough there was a little burn mark inside the rotor button. I ran down and got ANOTHER new one and the problem went away. Crazy I know but something to look at. Another thing you might do is run the car with the decklid open in the dark and look for any arc sparks around the plug wires and disty. You can actually see them in the dark pretty good. Good luck and peace Pete

I'll look at that tomorrow, but I did have the decklid open the night I replaced it and actually had my hand on the distributor adjusting the timing, but I didn't see or feel any sparks. I'll pull the dizzy off tomorrow after work and take a good look at it.

My guess is your timing is off, and you have a problem with your ICM to ECM. That includes ICM, wiring between the two, and the ECM.

My guess is also you have a second item that is making the SES light come on at times.

The issue that makes the light come on while driving could be a EGR control valve issue or an O2 issue. EGR control valve will not make much of a driving difference.

You do know how to find your tdc on your balancer so you can set your timing right?

quote Originally posted by phonedawgz: My guess is your timing is off, and you have a problem with your ICM to ECM. That includes ICM, wiring between the two, and the ECM. My guess is also you have a second item that is making the SES light come on at times. The issue that makes the light come on while driving could be a EGR control valve issue or an O2 issue. EGR control valve will not make much of a driving difference. You do know how to find your tdc on your balancer so you can set your timing right?

quote Originally posted by Rallaster: As far as proper timing is concerned, no, I haven't taken a timing light to it because the balancer is clocked wrong on the crank, so it's not perfect, but when it decides to run right it almost runs away.

quote Originally posted by Pete Matos: Here's another thing to check. One of the major problems I had at first was a miss problem that turned out to be a bad brand new distributor rotor button. It actually had a little crack in it and the spark found a way to ground and the car would occasionally run like crap. Once I had redone the disty including removing the shaft and cleaning it with some light sandpaper in my lathe and putting the new coil in it and everything else I could do to it I did a complete tuneup and it still had that miss. It was not until someone suggested it might be a short of some kind that I inspected the cap and rotor for cracks and sure enough there was a little burn mark inside the rotor button. I ran down and got ANOTHER new one and the problem went away. Crazy I know but something to look at. Another thing you might do is run the car with the decklid open in the dark and look for any arc sparks around the plug wires and disty. You can actually see them in the dark pretty good. Good luck and peace Pete

^^^X2, but mist that engine first to improve your chances.

But as long as the balancer outside ring isn't slipping you can put a mark on it at tdc.

Take a spark plug and knock out the center - Then install a bolt long enough in it to hit the top of the piston. Install it in cyl #1. Turn the crank clockwise till the piston is stopped by the bolt. Put a mark on the balancer next to the 0 tdc notch of the indicator. Now turn the engine counter clockwise till it stops again. Put a second mark on the balancer. TDC is the mid point those two marks. Make a permanent line there. MAKE SURE YOU REMOVE THE MODIFIED SPARK PLUG before you crank up the engine to set the timing.

TPS low -
Take a volt meter and with the key on, engine off - make sure you have +5v on the gray wire. If so replace the TPS.

VSS low
Does your speedo work?

[This message has been edited by phonedawgz (edited 09-10-2011).]

quote Originally posted by phonedawgz: But as long as the balancer outside ring isn't slipping you can put a mark on it at tdc. Take a spark plug and knock out the center - Then install a bolt long enough in it to hit the top of the piston. Install it in cyl #1. Turn the crank clockwise till the piston is stopped by the bolt. Put a mark on the balancer next to the 0 tdc notch of the indicator. Now turn the engine counter clockwise till it stops again. Put a second mark on the balancer. TDC is the mid point those two marks. Make a permanent line there. MAKE SURE YOU REMOVE THE MODIFIED SPARK PLUG before you crank up the engine to set the timing. TPS low - Take a volt meter and with the key on, engine off - make sure you have +5v on the gray wire. If so replace the TPS. VSS low Does your speedo work?

I'm going to have to look at doing the spark plug timing, I didn't think about doing it that way.

TPS is showing 5 volts, but it's still throwing a low TPS voltage code.

Speedo is inop -- mostly. The plug on the VSS is damaged, but the speedo goes in and out if I move the wiring harness. The VSS issue just started when I replaced the distributor.

Take a long pin and stick it up the backside of the middle conductor of the TPS. Then attach the positive lead of your volt meter to it. Put the negative lead on engine ground.



Now with the key on - engine off - read the voltage. Make sure you are reading a voltage. You might have to play around with the pin to get it to connect.You should have about 0.7v with the throttle closed, and it should increase smoothly till full throttle 4.5v. Any dropouts means your TPS is bad.

Then try the same with the MAP sensor.

Key on engine off you should read what this table says:


Engine idling you should read about 0.9v. Snap open the throttle and the voltage should pop up to about 4v. Letting the throttle shap shut the voltage should drop below 0.9v and then return to the idle position when the idle speed does.

[This message has been edited by phonedawgz (edited 09-10-2011).]

quote Originally posted by phonedawgz: Take a long pin and stick it up the backside of the middle conductor of the TPS. Then attach the positive lead of your volt meter to it. Put the negative lead on engine ground. Now with the key on - engine off - read the voltage. Make sure you are reading a voltage. You might have to play around with the pin to get it to connect.You should have about 0.7v with the throttle closed, and it should increase smoothly till full throttle 4.5v. Any dropouts means your TPS is bad. Then try the same with the MAP sensor. Key on engine off you should read what this table says: Engine idling you should read about 0.9v. Snap open the throttle and the voltage should pop up to about 4v. Letting the throttle shap shut the voltage should drop below 0.9v and then return to the idle position when the idle speed does.

I did that with the TPS and it was showing a steady 5.01 volts with no variation regardless of throttle position on the brown wire. I didn't check the other 2 wires, just the brown one.

I'll check the MAP sensor tomorrow in the daylight.

Brown wire eh?

I guess the 2.5 uses different color wires to the TPS.

The TPS gets fed to it +5v on one wire - Ground on the other wire. It returns a varying voltage on the third. On the 2.8 the 5v supply is on the gray wire. Ground is on the black wire. The signal is returned to the ECM on the blue wire.

See what you get on the other color wires.

This is the diagram from a '92 bonneville, but the 2.8 Fiero uses the same color wires


Don't get caught up on the voltages here - just again that you are looking for a smooth movement from idle to WOT with no drop outs. The only critical voltage is the idle voltage. It should be less than 0.9v so the ECM learns that it is idle.

FIXED IT!!

On my way to work this morning, it was spitting and sputtering like it was out of gas, yet the fuel gauge showed 1/2 tank with no SES. Ok, the first thing I think of is the fuel filter is clogged. After work I limp it to Advance Auto to get a new fuel filter and install it in the parking lot. That seems to fix it... for about 5 minutes. I'm now getting the SES light with the spitting and sputtering... GRRRR. About the time it starts sputtering again, I'm in front of an AutoZone. At this point I'm like, "screw it" I know from coding it 4 times in the last 3 days that the TPS is coding for low voltage, so I pull into AZ and see if they have a TPS in stock which they do, so I get it and while standing in the rain I replace the TPS in hopes of just shutting the damned SES light off. I get the new TPS installed and get in to start the engine and it doesn't even get a full rotation and it fires. It's idling smooth, no blips, no hesitations, no stutters. I go to pull out of AZ and I almost wind up backwards in the middle of the street. Whoa! The SES light is out, and it's running smooth as silk. I finish the drive home, about 45 miles and the fuel gauge doesn't move. I'll find out in the morning after letting it sit over night if the TPS solved everything. *crosses fingers* I'll post up tomorrow the results of it all and hopefully close this chapter in this engine.

as Phonedawgz would say.......

Cool Cool Cool..